AVIAN  FLUE  SURVEILLANCE ACTIVITIES 

 CENTRAL TEAM & DMO

           at KUMARAKOM on 4/12/2014 

Key facts

• Avian influenza (AI), commonly called bird flu, is an infectious viral disease of birds.
• Most avian influenza viruses do not infect humans; however some, such as A(H5N1) and A(H7N9), have caused serious infections in people.
• Outbreaks of AI in poultry may raise global public health concerns due to their effect on poultry populations, their potential to cause serious disease in people, and their pandemic potential.
• Reports of highly pathogenic AI epidemics in poultry, such as A(H5N1), can seriously impact local and global economies and international trade.
• The majority of human cases of A(H5N1) and A(H7N9) infection have been associated with direct or indirect contact with infected live or dead poultry. There is no evidence that the disease can be spread to people through properly cooked food.
• Controlling the disease in animals is the first step in decreasing risks to humans.

Avian influenza (AI) is an infectious viral disease of birds (especially wild water fowl such as ducks and geese), often causing no apparent signs of illness. AI viruses can sometimes spread to domestic poultry and cause large-scale outbreaks of serious disease. Some of these AI viruses have also been reported to cross the species barrier and cause disease or subclinical infections in humans and other mammals.

AI viruses are divided into 2 groups based on their ability to cause disease in poultry: high pathogenicity or low pathogenicity. Highly pathogenic viruses result in high death rates (up to 100% mortality within 48 hours) in some poultry species. Low pathogenicity viruses also cause outbreaks in poultry but are not generally associated with severe disease.

Avian influenza A(H5N1) and A(H7N9) background-The A(H5N1) virus subtype, a highly pathogenic AI virus, first infected humans in 1997 during a poultry outbreak in Hong Kong SAR, China. Since its widespread re-emergence in 2003 and 2004, this avian virus has spread from Asia to Europe and Africa and has become entrenched in poultry in some countries, resulting in millions of poultry infections, several hundred human cases, and many human deaths. Outbreaks in poultry have seriously impacted livelihoods, the economy and international trade in affected countries.

The A(H7N9) virus subtype, a low pathogenic AI virus, first infected 3 humans – 2 residents of the city of Shanghai and 1 resident of Anhui province - in March 2013. No cases of A(H7N9) outside of China have been reported. Containment measures, including the closure of live bird markets for several months, have impacted the agriculture sectors of affected countries and international trade. Continued surveillance for A(H7N9) will be necessary to detect and control the spread of the virus.

Ongoing circulation of A(H5N1) and A(H7N9) viruses in poultry, especially where endemic, continues to pose threats to public health, as these viruses have both the potential to cause serious disease in people and may have the potential to change into a form that is more transmissible among humans. Other influenza virus subtypes also circulate in poultry and other animals, and may also pose potential threats to public health.

Avian influenza A(H5N1) and A(H7N9) infections and clinical features in humans

The case fatality rate for A(H5N1) and A(H7N9) virus infections in people is much higher compared to that of seasonal influenza infections. The A(H7N9) virus particularly affects people with underlying medical conditions.

Clinical features---------In many patients, the disease caused by the A(H5N1) virus follows an unusually aggressive clinical course, with rapid deterioration and high fatality. Like most emerging disease, A(H5N1) influenza in humans is not well understood.

The incubation period for A(H5N1) avian influenza may be longer than that for normal seasonal influenza, which is around 2 to 3 days. Current data for A(H5N1) infection indicate an incubation period ranging from 2 to 8 days and possibly as long as 17 days. Current data for A(H7N9) infection indicate an incubation period ranging from 2 to 8 days, with an average of five days.¹ WHO currently recommends that an incubation period of 7 days be used for field investigations and the monitoring of patient contacts.Initial symptoms include high fever, usually with a temperature higher than 38°C, and other influenza-like symptoms (cough or sore throat). Diarrhea, vomiting, abdominal pain, chest pain, and bleeding from the nose and gums have also been reported as early symptoms in some patients.

One feature seen in many patients is the development of lower respiratory tract early in the illness. Respiratory distress, a hoarse voice, and a crackling sound when inhaling are commonly seen. Sputum production is variable and sometimes bloody.²Complications of A(H5N1) and A(H7N9) infection include hypoxemia, multiple organ dysfunction, and secondary bacterial and fungal infections.³

Antiviral treatment-Evidence suggests that some antiviral drugs, notably oseltamivir, can reduce the duration of viral replication and improve prospects of survival.In suspected cases, oseltamivir should be prescribed as soon as possible (ideally, within 48 hours following symptom onset) to maximize its therapeutic benefits. However, given the significant mortality currently associated with A(H5N1) and A(H7N9) infection and evidence of prolonged viral replication in this disease, administration of the drug should also be considered in patients presenting later in the course of illness. The use of corticosteroids is not recommended.In cases of severe infection with the A(H5N1) or A(H7N9) virus, clinicians may need to consider increasing the recommended daily dose or/and the duration of treatment.In severely ill A(H5N1) or A(H7N9) patients or in patients with severe gastrointestinal symptoms, drug absorption may be impaired. This possibility should be considered when managing these patients.⁴ Moreover, most A(H5N1) and A(H7N9) viruses are predicated to be resistant to adamantine antiviral drugs, which are therefore not recommended for use.

Risk factors for human infection-The primary risk factor for human infection appears to be direct or indirect exposure to infected live or dead poultry or contaminated environments, such as live bird markets. Controlling circulation of the A(H5N1) and A(H7N9) viruses in poultry is essential to reducing the risk of human infection. Given the persistence of the A(H5N1) and A(H7N9) viruses in some poultry populations, control will require long-term commitments from countries and strong coordination between animal and public health authorities.There is no evidence to suggest that the A(H5N1)and A(H7N9) viruses can be transmitted to humans through properly prepared poultry or eggs. A few A(H5N1) human cases have been linked to consumption of dishes made of raw, contaminated poultry blood. However, slaughter, defeathering, handling carcasses of infected poultry, and preparing poultry for consumption, especially in household settings, are likely to be risk factors.

Human pandemic potential-Influenza pandemics (outbreaks that affect a large proportion of the world due to a novel virus) are unpredictable but recurring events that can have health, economic and social consequences worldwide. An influenza pandemic occurs when key factors converge: an influenza virus emerges with the ability to cause sustained human-to-human transmission, and the human population has little to no immunity against the virus. With the growth of global trade and travel, a localized epidemic can transform into a pandemic rapidly, with little time to prepare a public health response.The A(H5N1) and A(H7N9) AI viruses remain two of the influenza viruses with pandemic potential, because they continue to circulate widely in some poultry populations, most humans likely have no immunity to them, and they can cause severe disease and death in humans.

However, whether the influenza A(H7N9) virus could actually cause a pandemic is unknown. Experience has shown that some animal influenza viruses that have been found to occasionally infect people have not gone on to cause a pandemic while others have done so. Surveillance and the investigations now underway will provide some of the information needed to make this determination.

In addition to A(H5N1) and A(H7N9), other animal influenza virus subtypes reported to have infected people include avian H9, and swine H1 and H3 viruses. H2 viruses may also pose a pandemic threat. Therefore, pandemic planning should consider risks of emergence of a variety of influenza subtypes from a variety of sources.

LEFT FOR HER ETERNAL REST ON 17/11/2014

                        ആദരാഞ്ജലികള്‍

HIV pandemic's origins located: It may have emerged in Congo in 1920s?

Scanning electron micrograph of an HIV-infected H9 T cell. Credit: NIAID

The HIV pandemic with us today is almost certain to have begun its global spread from Kinshasa, the capital of the Democratic Republic of the Congo (DRC), according to a new study.

An international team, led by Oxford University and University of Leuven scientists, has reconstructed the genetic history of the HIV-1 group M pandemic, the event that saw HIV spread across the African continent and around the world, and concluded that it originated in Kinshasa. The team's analysis suggests that the common ancestor of group M is highly likely to have emerged in Kinshasa around 1920 (with 95% of estimated dates between 1909 and 1930).

HIV is known to have been transmitted from primates and apes to humans at least 13 times but only one of these transmission events has led to a human pandemic. It was only with the event that led to HIV-1 group M that a pandemic occurred, resulting in almost 75 million infections to date. The team's analysis suggests that, between the 1920s and 1950s, a 'perfect storm' of factors, including urban growth, strong railway links during Belgian colonial rule, and changes to the sex trade, combined to see HIV emerge from Kinshasa and spread across the globe.

A report of the research is published in this week's Science.

'Until now most studies have taken a piecemeal approach to HIV's genetic history, looking at particular HIV genomes in particular locations,' said Professor Oliver Pybus of Oxford University's Department of Zoology, a senior author of the paper. 'For the first time we have analysed all the available evidence using the latest phylogeographic techniques, which enable us to statistically estimate where a virus comes from. This means we can say with a high degree of certainty where and when the HIV pandemic originated. It seems a combination of factors in Kinshasa in the early 20th Century created a 'perfect storm' for the emergence of HIV, leading to a generalised epidemic with unstoppable momentum that unrolled across sub-Saharan Africa.'

'Our study required the development of a statistical framework for reconstructing the spread of viruses through space and time from their genome sequences,' said Professor Philippe Lemey of the University of Leuven's Rega Institute, another senior author of the paper. 'Once the pandemic's spatiotemporal origins were clear they could be compared with historical data and it became evident that the early spread of HIV-1 from Kinshasa to other population centres followed predictable patterns.'